High-frequency heating tool



Aug. 12, 1952 KIUS TA 2,606,997

I HIGH-FREQUENCY HEATING TOOL Filed Sept. 28, 195o 2 SHEETS-SHEET 1 \ve nfor5 /a Beck/us H090 L nd5from A3},

1952 1. BECKIUS ET AL 7 2,606,997

HIGH-FREQUENCY HEATING TOOL Filed Sept. 28, 1950 2 SHEETS-SHEET 2 Patented Aug. 12, 1952 HIGH-FREQUENCY HEATING TOOL Ivar Beckius and Hugo Lindstriim, Vastera s, Swe den, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation 1 V of Sweden Application September 28, 1950, Serial No. 187,280 In'Sweden June 16,1950

'Claims. (01. 219-47 When heating the ends of bolts, cross edges of borers or the like by means of high frequency currents it is difficult with the conventional tools hitherto known to heat the center portion of the work-piece by direct heat development in this portion. Usually this portion gets its heat through conduction from the outer portions. This results in a comparatively high power requirement and therefore in a rather low efficiency. It is the object of the present invention to eliminate these drawbacks and to furnish a handy, simple and comparatively cheap tool.

The invention relates to a high frequency induction tool for heating end surfaces of longitudinally extending objects of metal. The pr ncipal feature of this invention is that the heating conductors supplied from a high frequency transformer are embedded in an iron core and arranged in conformity to those portions of the end surface which preferably have to be heated, and that every second heating conductor is arranged to lead the heating current to a common star connection point within the end surface, while each other heating conductor leads the current from the same. In this manner, besides a reliable heating of those portions of the workpiece which have preferably to be heated, a heat concentration towards the centre of its surface is attained.

The invention will now be described with reference to the accompanying drawing and other features of the invention will be pointed out.

Figs. 1, 2 and 3 show an embodiment of the invention intended to be used when the heatin of substantially plane end surfaces of workpieces is concerned, e. g. of cross edges of a borer, while Figs. 4, 5 and 6 show an embodiment of the tool according to the invention wherein also the side portions near the end surface of the work-.

piece have to be heated.

Figs. 1 and 4 show diagrammatically the wiring connections and the direction of the currents in both alternatives, I

Figs. 2 and 5, respectively, show on the right hand sides sections and on the left hand sides elevation views of the corresponding tools, and

Figs. 3 and 6 show the tools viewed from below. Insofar as the same elements are used in both alternatives, the reference numerals are chosen alike. It should be noticed that structural modiiications are possible within the scope of the invention. For instance, the heating conductor arrangement may consist of six conductors instead of four as shown on the drawing.

Referring to. Figs. 1 and 4, the numeral 1 indicates a supplytransformer, thesecondary of which is connected to; two interconnecting. conductors 2 and 3, respectively, e. g. bars. The heating conductors 4 andi, respectively, are connected through cylindrical intermediate. conductors 4' and 5, respectively, to the'conductors 2 and 3, respectively, in such a manner that every second conductor leads the current to, a common start connection point and every other second conductor leads the current away from the same. The conductors 4 and 5 are preferably hollow and provided with nozzles or the like for a cooling fluid. The conductors 4 and 5 are laid within slots 6 in an iron core 1, which is preferably made of helically wound sheet band, the inner diameter of which core is smaller than the width of the heating conductors 4 and 5. The surfaces of the heating conductors facing the work-piece 8 lie somewhat under the end surface of the iron core. The active heating portion has the shape of a cross.

The tool according to Figs. 4 to 6 has heating conductors 4 and 5, which are formed to conform also to the side portions of the work-piece near its end surface. In order to augment the induction, a preferably closed laminated ring sheet iron core 9 surrounds the portions of the conductors which extend in a direction parallel to the sides of the work-piece.

We claim as our invention:

1. A high frequency induction tool for heating end surfaces of longitudinally extending objects of metal, comprising an iron core having heating conductors partly embedded therein and arranged in conformity to those portions of the said end surfaces which preferably have to be heated, every second heating conductor being arranged to lead the heating current to a common star connection point within the end surface, while every other heating conductor leads the current away from the same.

2. A high frequency induction tool for heating end surfaces of longitudinally extending objects of metal, comprising heating conductors partly embedded therein and arranged in conformity to those portions of the end surface which preferably have to be heated, every second heating conductor being arranged to lead the heating current to a common star connection point within the end surface, while every other heating conductor leads the current away from the same, and an iron core of helically wound sheet iron band, the inner diameter of said core being less than the width of the heating conductors.

3. A high frequency induction tool for heating and surfaces of longitudinally extending objects of metal, comprising an iron core, heating conductors partly embedded therein and arranged in conformitygtogthose portionsof the end surfaces which 'preferably have to beiheated, every second heating conductor being arranged to lead the heating current to a common star connection I point within the end surface, while every other heating conductor leads the current away from the same, the surfaces of the heating conductors facing the work piece being" located somewhat 4 under the surface of the ironc'orei 4. A high frequency induction tool for heating end surfaces of longitudinally extending objects of metal, comprising an iron core, heating con 4 5. A high frequency induction tool according to claim 4, comprising a separate laminated sheet core surrounding the conductors adjacent to said side portions.

' 'IVAR BECKIUS.

HUGO LIN'DSTROM.

REFERENCES CITED The following references are of record in the file of this patent:

V 1 "UNITED STATES PATENTS Number I 5 Name Date 1,413,053 'Onstad Apr. 18, 1922 1,827,274 7 Willcox Oct. 13, 1931 2,352,332 Limpel June 27, 1944 2,493,771 Marquardt et a1. Jan. 10, 1950 FOREIGN PATENTS Number Country Date 74,830 .Switzerland Apr. 16, .1917 487,385 Great Britain June 1'7, 1938 715,434 France Aug. 25, 1930 

